At 74 I understand the importance of not pushing my body beyond a reasonable limit. For toning up and stregnth training I lift weights on alternate days. 1 day of rest in between is really important. For cardio, on the other hand, I shoot for 4-5 times per week. Regardless of the exercise I focus on slow controlled and sustained movement - a little stress without strain is the goal. The old saying: "No pain, no gain" was WRONG and potentially dangerous. If you never heard of building collateral circulation look it up or ask me. Slow and steady wins the game. Any other views or comments? Please share.